I have a few questions about posi. They might have already been answered, but just want a better understanding. Thanks

1. my 85 gmc is used as a daily driver pickup. Which would be better for it, posi or limited slip? Im looking for something with a quick start and nice burnouts.
2. My axles are probley from 85, should i replace them or will they be fine. They have suffered alot of with only one wheel spinning.
3. Which brand of posi/limited slip would be the most easiest to install? Ill be the one installing it.